Project Summary One of the primary ways in which infants learn about the world is through their own actions and interactions with other people, particularly parents and caretakers. This project proposal focuses on the cognitive skills that underlie successful parent-child interactions in profoundly deaf infants who receive cochlear implants. Cochlear implantation is currently the leading intervention for infants with profound hearing loss. Cochlear implants (CIs) provide access to sound for deaf populations, enabling spoken language acquisition and the social development that accompanies it. However, not all infants who receive CIs achieve age-appropriate language outcomes. Further, there is an enormous degree of variability in their outcomes, which extends to general cognitive functioning. So far, research aimed at identifying sources of this variability has focused on audiological and demographic factors, but has largely ignored the underlying cognitive factors that guide their learning mechanisms and social interactions. The proposed research will address this gap by investigating action prediction?the ability to visually anticipate goal-directed actions?and joint coordination abilities during parent-child interactions. Action prediction is a nonverbal cognitive skill forms the basis for social-cognitive development but has never been examined deaf infants. This project will use innovative, head-mounted eye- tracking methodology to determine how early deafness affects action and interaction skills in deaf infants (implanted before 18 months of age) and a comparison group of normal-hearing, age-matched controls. We will next examine links between these skills and their receptive and expressive language growth. Deaf infants will be assessed longitudinally before and after cochlear implantation to identify how their action skills change following implantation, and how they compare with the development of hearing infants. Finally, we will relate the outcomes of these experiments to standardized measures of expressive and receptive language, in order to better understand the pathways through which deafness influences language outcomes in CI users. This research will provide important new information for parents and clinicians that will aid in identifying new targets for therapy in order to maximize learning opportunities and successful social interactions for these infants. It will also shed light on the challenges that deaf infants face during parent-child interactions, which can be then used to inform intervention strategies that form part of the clinical care for deaf infants post-implantation. Further, this research will contribute new knowledge about the role of early auditory experiences in cognitive and social development which will be of general relevance to the field of developmental research.